Why won't 3 screws near battery go back in, after display install?

I have two a1229s and I recently swapped out a full display assembly following the manual on ifixit. Everything went fine except I can't get 3 screws back in

These 3 - http://guide-images.ifixit.net/igi/WKwoX...

(the ones under the battery, on the opposite side of the battery as the ram door; they're tilted at an angle)

First, I'm not certain which screws go back there, because i combined the screws from both mbps, and don't necessarily plan on reassembling the other one, as I'll probably just sell the parts).

I assume it's the short screw with the large head, but I tried every different type of screw and none would lock in. I feel like I could probably just manage fine without having these three screws in there, but if anyone knows how to fix this issue, or can even tell me for sure which screws should go in there (though, I made a good effort with all of them - and all 3 holes - so that's not the main issue), I would be interested and appreciative.